Crack Paths 2006

T x E ' ˜ ˜ ˜

D

amb x ) ( V

amb

(2)

x T R ' ˜ ˜ ) 1 ( D

amb

In table 3 are shown residual stresses values for T = 200, 400, 600, 800, 1000 K, at

diferent xamb values or equivalent depth of the new layer. Using residual stresses

calculated for T = 200, 400, 600, 800, 1000 K (Table 3), new predictions regarding

crack propagation were made (Table 4). As expected, the number of cycles to failure

dramatically decreases with the increase of residual stresses ( Tincreases).

Figure 5. Predictions of crack c lengths [m] against number of cycles for a tank wagon

railway axle with no residual stresses starting from different initial crack sizes.

Table 3. Calculated residual stresses values

V[MPa] at T = 400K V[MPa]at T = 600K V[MPa] at T = 800K V[MPa] at

x amb

T = 1000K

0.000

80.57

121.13

200.48

161.74

0.001

65.43

98.38

131.64

165.01

0.002

48.89

75.02

100.24

125.35

0.003

33.77

50.77

67.86

84.79

0.004

17.19

25.85

34.73

43.10

0.005

0.00

0.00

0.00

0.00